1. Field of the Invention
The present invention relates to a non-contact type IC card, comprising a plane coil and a semiconductor element, wherein terminal portions of the plane coil and electrode terminals of the semiconductor element are electrically connected to each other, and a process for manufacturing the IC card.
2. Description of the Related Art
A structure of a prior art non-contact type IC card will be described with reference to FIGS. 6(a) and 6(b).
The plane coil 52 is prepared by etching a metallic foil (for example, a copper foil) formed on one surface of a thin insulating resinous substrate, such as a resinous film, to have a generally rectangular coil shape or by printing a electro-conductive paste in a coil shape on one surface of the thin insulating resinous substrate 54 and drying the same. Opposite ends of the plane coil 52 define terminal portions 52a, respectively.
A semiconductor element 56 has two electrode terminals 58 projected from one surface thereof to be connected with the respective terminal portions 52a of the plane coil 52.
As shown in FIG. 7, the semiconductor element 56 is positioned and attached onto one surface of the thin insulating resinous substrate 54 so that two electrode terminals 58 of the semiconductor element 56 are extended over a part of the plane coil 52 and are located in alignment with the respective terminal portions 52a of the plane coil 52.
More concretely, as shown in FIG. 8, the semiconductor element 56 is press-fitted onto the thin insulating resinous substrate 54 via an anisotropic conductive film 60. Thereby, an electro-conductive path is formed between the projected electrode terminal 58 and the terminal portion 52a opposite thereto so that the electrode terminal 58 is electrically connected to the terminal portion 52a of the plane coil 52.
A pair of resinous over-sheets 62, each carrying an adhesive layer on one surface thereof, are placed, respectively, on both sides on the thin insulating resinous substrate 54 on which are disposed the plane coil 52 and the semiconductor element 56, and heated under pressure to form a non-contact type IC card 50, as shown in FIGS. 6(a) and 6(b).
Recently, as the semiconductor element 56 has become increasingly smaller in size, the gap between the pair of electrode terminals 58 formed on the semiconductor element 56 has also become smaller, whereby it is impossible to locate the semiconductor element 56 so that the electrode terminals 58 thereof are arranged inside and outside the plane coil 52.
As a countermeasure to this problem, it has been proposed that one of the terminal portions 52a of the plane coil 52 (for example, the inside terminal portion 52a) can be located at a position outside the plane coil 52 in the vicinity of the other terminal portion 52a, while the plane coil 52 is bridged via the opposite surface of the thin insulating resinous substrate 54 as shown in FIGS. 9 and 10.
According to this structure, even if the semiconductor element 56 only has a small gap between the electrode terminals 58, it is possible to locate the semiconductor element 56 at a position on the one surface of the thin insulating resinous substrate 54 without bridging over the plane coil 52, and to electrically connect the electrode terminals 58 to the terminal portions 52a of the plane coil 52 while using the same mounting structure as in the preceding example.
In this regard, the above-mentioned IC card relating to the prior art is disclosed in the U.S. Pat. No. 5,705,852 (issued on Jan. 6, 1998).
However, in the structure shown in FIGS. 9 and 10, it is necessary to adhere metallic foils onto both surfaces of the thin insulating resinous substrate 54, form the plane coil 52 as well as an extension wiring pattern 64 by etching the metallic foils and provide a through-hole 66 to electrically connect the plane coil 52 formed on one surface with the extension wiring pattern 64 formed on the other surface. This results in an increase in production steps. Also, since it is necessary to use the thin insulating resinous substrate having the metallic foils adhered to the opposite surfaces thereof, there is a problem in that a material cost becomes higher to increase the product cost.
Thus, an object of the present invention is to provide a non-contact type IC card capable of mounting thereon a small-sized semiconductor element having a narrow gap between electrode terminals, without forming a circuit pattern on a surface of an thin insulating resinous substrate opposite to the surface on which a plane coil is formed.
Another object of the present invention is to provide a non-contact type IC card which solves the above-mentioned problems in the prior art.
According to the present invention, there is provided a non-contact type IC card comprising: an insulating film having first and second surfaces; a plane coil arranged on the first surface of the film, the plane coil having terminals; a semiconductor element arranged on the first surface of the film, the semiconductor element having electrode terminals; the film having through holes which expose the terminals of the plane coil and the electrode terminals of the semiconductor element to the second surface of the film; and a wiring pattern consisting of conductive paste, filled in the through holes and extending therebetween along the second surface of the film so that the terminals of the plane coil are electrically connected to the electrode terminals of the semiconductor element by means of the wiring pattern.
A gold-bump is provided on the electrode terminal of the semiconductor element and arranged within the through hole to facilitate an electrical connection between the conductive paste and the electrode terminal.
The terminal of the plane coil, exposed in the through hole, is plated with gold to facilitate an electrical connection between the conductive paste and the terminal of the plane coil.
According to another aspect of the present invention, there is provided a non-contact type IC card comprising: an insulating film having first and second surfaces; a plane coil arranged on the first surface of the film, the plane coil having terminals; a semiconductor element arranged on the second surface of the film, the semiconductor element having electrode terminals; the film having through holes at positions where the electrode terminals of the semiconductor element are exposed by means of the through holes; and a wiring pattern consisting of conductive paste, filled in the through holes and extending therefrom to the terminals of the plane coil so that the terminals of the plane coil are electrically connected to the electrode terminals of the semiconductor element by means of the wiring pattern. In this connection, the plane coil where the wiring pattern is to cross the plane coil is covered with an insulator and the wiring pattern is formed on the insulator.
According to still another aspect of the present invention, there is provided a process for manufacturing a non-contact type IC card comprising the following steps of: forming a plane coil on a first surface of an insulating film; forming a film with through holes at positions where terminals of the plane coil and electrode terminals of a semiconductor element are to be exposed by the through holes to a second surface of the film; mounting the semiconductor element on the first surface of the film so that electrode terminals thereof are positioned in the through holes; and printing conductive paste so as to be filled in the through holes and extending therebetween along the second surface of the film to form a wiring pattern for electrically connecting the terminals of the plane coil to the electrode terminals of the semiconductor element.
According to further aspect of the present invention, there is provided a process for manufacturing a non-contact IC card comprising the following steps of: forming a plane coil on a first surface of an insulating film; forming a film with through holes at positions where electrode terminals of a semiconductor element are to be exposed by the through holes; mounting the semiconductor element on the second surface of the film so that electrode terminals thereof are positioned at the through holes; and printing conductive paste so as to be filled in the through holes and extending along the first surface of the film to form a wiring pattern for electrically connecting the terminals of the plane coil to the electrode terminals of the semiconductor element. In this connection, the plane coil is covered with an insulator where the wiring pattern will across the plane coil and, then, the conductive paste of the wiring pattern is pasted on the insulator.
The plane coil forming step can comprise preparing a substrate comprising the film to which a copper foil is previously adhered and then etching the copper foil. The plane coil forming step can also comprise printing conductor paste on the film.
A gold-bump is plated on the electrode terminal of the semiconductor element, before the semiconductor element is mounted on the first surface of the film.
The terminal of the plane coil is plated with gold, after the through hole is formed.